Rat hearts with coronary circulations perfused by the Langendorff technique were studied. Recordings were made of the electrical and mechanical activity. Once the rate and rhythm of each heart and stabilized it was perfused with Ringer-Locke solution for 90 minutes; frusemide (40 μg/ml) was added to the perfusate during the last 30 minutes of this period. Eighteen experiments were performed—six controls, six in which prolactin at a concentration of 50 ng/ml was added to the perfusate for the whole 90 minutes, and six in which a prolactin concentration of 200 ng/ml was used. With the controls heart rate and rhythm remained steady, but there was a slow decline in amplitude of the contraction. With a prolactin concentration of 50 ng/ml the heart rate rose to about 40% above control during the first hour and after an initial sharp increase the contraction amplitude declined more rapidly than in the controls. The prolactin concentration of 200 ng/ml produced a decline of about 25% in heart rate over the first hour and amplitude behaved much as in the controls. Frusemide had no clear effect on the rate of beating of the controls, but it tended to reverse both the acceleration produced by 50 ng/ml prolactin and the slowing produced by the higher dose. Both the doses of prolactin consistently caused disturbances of rhythm. These effects occur at concentration of prolactin found in human plasma in various pathophysiological conditions.
Bromocriptine administered both orally and intravenously potentiated gastric acid secretion in response to submaximal pentagastrin stimulation in cats. Bromocriptine did not increase the maximum acid secretion in response to pentastrin, not did it stimulate basal acid secretion. Potentiation was observed in normal and vagotomized animals which precludes involvement of the vagi in the response. The mechanism of action of this compound on the stomach does not appear to be mediated through stimulation of dopaminergic receptors as no potentiation was observed with dopamine infusions. It is argued that the bromocriptine potentiation of gastric acid secretion may be a demonstration of 5-hydroxytryptamine or alpha-adrenergic antagonism. However, the potentiation observed with daily oral bromocriptine treatment had disappeared by the eighth day and may correlate with the disappearance of gastric side effects noted in patients on bromocriptine treatment.
1. A method is described for the bio-assay of gastrin activity in the anaesthetized cat, based on the acid stimulating activity of gastrin.2. A ;gastrin' of unknown potency can be assayed in terms of a stable Standard Gastrin Extract or of Synthetic Human Gastrin I.3. The sensitivity of the method is such that it will detect quantities of Synthetic Human Gastrin I at least as small as those at present described as detectable by radioimmunological techniques.4. The precision of the assay is such that it falls in the category that has been described as very precise and well suited to clinical studies.
1. The effect of Saffan (alphaxalone and alphadolone acetate) and Nembutal (pentobarbitone) anaesthesia on gastric acid secretion stimulated by I.V. bolus injections of pentagastrin was investigated in the gastric fistula cat. The effect of Saffan anaesthesia was also tested on I.V. near-maximal and sub-maximal infusions of pentagastrin. 2. Neither anaesthetic reduced the acid secreted in response to bolus injections of pentagastrin. Increased acid secretion with the anaesthetic was noted at some doses of pentagastrin in both intact and vagotomized animals. 3. Saffan anaesthesia had no effect on near-maximal gastric acid secretion stimulated by pentagastrin 8 microgram kg-1 hr-1 but increased the response to pentagastrin 1 microgram kg-1 hr-1. 4. It is suggested that the differences in the acid secretory responses of the anaesthetized acutely prepared animal compared with the conscious animal are a consequence of the surgical procedures rather than the state of consciousness.
1. The effects of cimetidine, somatostatin and atropine upon the outputs of acid, pepsin, prostaglandins (PG) E and F in gastric juice secreted in response to i.v. infusions of pentagastrin and histamine (H) have been studied in the conscious gastric fistula cat. 2. At constant rate infusions secretion of PGE occurs and follows a similar pattern to that of gastric acid. However the ratio of H:PGE varies considerably and to an extent inexplicable in terms of assay variation. 3. Inhibition of acid output is matched by inhibition of the output of PGE, but changes in concentration of PGE suggest this is a volume related phenomenon. 4. It is concluded that gastric juice PGE is most unlikely to have a regulatory effect upon acid secretion.
The two major categories of factors known to influence adult sexual behavior potentials are the relative amounts of androgen present during specific stages of perinatal ontogeny and adequate social stimulation during prepuberal development. The possible interaction between these two was evaluated by characterizing the ejaculatory and lordotic behavior potentials of prenatally stressed and control male rats that had been weaned at 16 days of age and raised either in total social isolation or with a same-age female, a control male, or a prenatally stressed male. The decrement in male sexual behavior produced by prenatal stress was attenuated by raising the male with either a female or a control male. Social isolation alone or in combination with stress resulted in severely deficient male behavior. Peripheral skin shock promoted ejaculatory behavior in many previously noncopulating prenatally stressed males raised with other stressed males, but it was ineffective in most isolated animals. The high lordosis potential characteristic of prenatally stressed male rats was slightly lower in the group with a female cagemate and was markedly decreased by social isolation. These results support and extend the finding by Dunlap, Zadina, and Gougis (1978) that prenatal hormonal events and prepuberal rearing conditions can interact to attenuate or accentuate the effects that either treatment alone has on the development of adult sexual behavior potentials.
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